INVESTMENTS - Gross Unrealized Losses and Fair Value by Length of Time in Unrealized Loss Position (Detail) $ in Thousands	Mar. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	458	464
Fair Value
Less Than 12 Months	$ 243,369	$ 779,965
12 Months or More	932,751	400,181
Total	1,176,120	1,180,146
Unrealized Losses
Less Than 12 Months	6,640	79,408
12 Months or More	124,951	72,974
Total	$ 131,591	$ 152,382
U.S. treasuries and government agencies
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	10	10
Fair Value
Less Than 12 Months	$ 12,638	$ 53,139
12 Months or More	82,452	40,483
Total	95,090	93,622
Unrealized Losses
Less Than 12 Months	318	3,653
12 Months or More	5,704	3,651
Total	$ 6,022	$ 7,304
State and municipal
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	125	130
Fair Value
Less Than 12 Months	$ 35,791	$ 200,439
12 Months or More	233,683	62,482
Total	269,474	262,921
Unrealized Losses
Less Than 12 Months	719	30,803
12 Months or More	47,157	25,723
Total	$ 47,876	$ 56,526
Mortgage-backed and asset-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	323	324
Fair Value
Less Than 12 Months	$ 194,940	$ 526,387
12 Months or More	616,616	297,216
Total	811,556	823,603
Unrealized Losses
Less Than 12 Months	5,603	44,952
12 Months or More	72,090	43,600
Total	$ 77,693	$ 88,552